Results 1 to 4 of 4

Thread: Finding the relationship between two graphs

  1. #1
    New Member
    Join Date
    Feb 2012
    Posts
    2

    Finding the relationship between two graphs

    I have two graphs g(x) = -2x-3 and h(x) = (1/2)x. I have graphed each linear function, found the range and domain, but I am having trouble describing the relationship between the two graphs. My original answer was that if you remove the y-intercept from g(x), the graph of h(x) is obtained by vertically shrinking g(x) and then reflecting it about the x-axis. This was wrong. Can someone help steer me in the right direction. Thanks.

  2. #2
    Junior Member
    Join Date
    Feb 2012
    Location
    Germany
    Posts
    223
    Quote Originally Posted by katpul View Post
    I have two graphs g(x) = -2x-3 and h(x) = (1/2)x. I have graphed each linear function, found the range and domain, but I am having trouble describing the relationship between the two graphs. My original answer was that if you remove the y-intercept from g(x), the graph of h(x) is obtained by vertically shrinking g(x) and then reflecting it about the x-axis. This was wrong. Can someone help steer me in the right direction. Thanks.
    It's guessing on my side, but:

    If two lines [TEX]l_1[/TEX] and [TEX]l_2[/TEX] have the slopes [TEX]m_1[/TEX] and [TEX]m_2[/TEX] respectively and the slopes have the property:

    [TEX]m_1 \cdot m_2 = -1[/TEX]

    then the lines are perpendicular to each other:

    [TEX]m_1 \cdot m_2 = -1~\implies~l_1\ \perp \ l_2[/TEX]

  3. #3
    Senior Member
    Join Date
    Nov 2004
    Location
    Seattle
    Posts
    1,399
    I have two graphs g(x) = -2x-3 and h(x) = (1/2)x. I have graphed each linear function, found the range and domain, but I am having trouble describing the relationship between the two graphs. My original answer was that if you remove the y-intercept from g(x), the graph of h(x) is obtained by vertically shrinking g(x) and then reflecting it about the x-axis. This was wrong. Can someone help steer me in the right direction. Thanks.
    Look at the slopes of the two lines: -2 and 1/2. Notice anything about these values? They are negative reciprocals of each other. Does that sound familiar? It means that the lines are perpendicular to each other.

  4. #4
    New Member
    Join Date
    Feb 2012
    Posts
    2

    Thank You

    Thank you guys. This is one of those things where it is so simple and obivious I just couldn't see it.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •